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31.
A protein-tyrosine-phosphatase (PTPase; EC 3.1.3.48) containing two Src homology 2 (SH2) domains, SHPTP1, was previously identified in hematopoietic and epithelial cells. By placing the coding sequence of the PTPase behind a bacteriophage T7 promoter, we have overexpressed both the full-length enzyme and a truncated PTPase domain in Escherichia coli. In each case, the soluble enzyme was expressed at levels of 3-4% of total soluble E. coli protein. The recombinant proteins had molecular weights of 63,000 and 45,000 for the full-length protein and the truncated PTPase domain, respectively, as determined by SDS/PAGE. The recombinant enzymes dephosphorylated p-nitrophenyl phosphate, phosphotyrosine, and phosphotyrosyl peptides but not phosphoserine, phosphothreonine, or phosphoseryl peptides. The enzymes showed a strong dependence on pH and ionic strength for their activity, with pH optima of 5.5 and 6.3 for the full-length enzyme and the catalytic domain, respectively, and an optimal NaCl concentration of 250-300 mM. The recombinant PTPases had high Km values for p-nitrophenyl phosphate and exhibited non-Michaelis-Menten kinetics for phosphotyrosyl peptides. 相似文献
32.
Normally a complicated three-dimensional (3-D) approach is needed to study the field pattern of induction machines with skewed rotor bars. In this paper, a time-stepping two-dimensional (2-D) eddy-current finite element method, based on multislice technique, is described to study the steady-state operation and the starting process of skewed rotor induction machines. The fields of the multislices are being solved en bloc simultaneously, and thus, the effects of the eddy current and saturation can be taken into account directly. New forms of the governing equations for the multislice model are derived, which allow the meshes of multislices to be taken as one 2-D mesh so that the algorithm is very similar to that of general 2-D problems. Special techniques required for the mesh generation in the multislice model and the salient structures of the software are also described. The results obtained by using the program being developed have very good correlation with test data 相似文献
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Carl A. Soderstrom Patricia C. Dischinger Gordon S. Smith J.Richard Hebel David R. McDuff David A. Gorelick Timothy J. Kerns Shiu M. Ho Kathleen M. Read 《Accident; analysis and prevention》1997,29(6):715-721
A structured in-depth interview employing standardized criteria was used to determine the prevalence of lifetime and current alcohol dependence (alcoholism) in unselected consecutive patients admitted to a regional Level I trauma center. Of 629 patients, 157 (25.0%) were current alcoholics at the time of injury. An additional 87 (13.8%) were diagnosed as lifetime non-current alcoholics. There was no significant difference in the rates of current alcohol dependence among patients injured in vehicular crashes (23.5%), other unintentional trauma victims (29.3%), and those injured as a result of violence (24.6%). Of BAC + (blood alcohol concentration positive) patients, 54.5% were current alcoholics. However, 14.4% of alcohol-negative patients were also diagnosed as alcohol dependent. 相似文献
36.
Shye Lin Wu Chung Len Lee Tan Fu Lei Chen C.F. Chen L.J. Ho K.Z. Ling Y.C. 《Electron Device Letters, IEEE》1994,15(4):120-122
In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p+-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900°C. As a result, the junction depth of the BF2-implanted device is much larger than that of the boron-implanted device 相似文献
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Ho A.N. Pantell R.H. Feinstein J. Huang Y.C. 《Quantum Electronics, IEEE Journal of》1991,27(12):2650-2655
A novel wiggler design for use in free-electron lasers (FELs) is proposed, consisting of a staggered array of magnetic poles situated inside the bore of a solenoid. The resultant field pattern consists of a periodic transverse magnetic field on axis, as well as a longitudinal guide field. Such a wiggler has several advantages: the longitudinal field acts to confine the electrons near the FEL axis, high fields can be attained at short wiggler periods, the field strength is easily varied, and fabrication and testing of the wiggler are relatively easy. It is planned to use this wiggler design in a far infrared FEL to be built at Stanford University 相似文献
39.
JaeHyunKim JounHoLee JiChulLim ChangHoonLee MooHyoungSong JuYeonYoon HeeDongChoi JeomJaeKim ChangHoOh SangDeogYeo 李路海 《现代显示》2004,31(5):31-33
薄膜晶体管液晶电视(TFT-LCD TV)因为具有薄、轻、紧凑和可随意放置的特点,已经占据了大部分电视机市场。除了这些物理特性以外,最重要的特性是已具有了良好像质的对比度。为了将对比度提高到1:600以上,对偏振片膜、背光源板、滤色片树脂、电极锥角和摩擦条件等都进行了研究。优化的背光板组合,光滑的电极锥角和摩擦方法的控制是提高对比度的主要控制因素。应用新开发的滤色片树脂,对获得高对比度最为有效。 相似文献
40.
The stability of five major phenolics, namely (−)-epicatechin (EC), procyanidin B2 (PC-B2), chlorogenic acid (ChA), hyperoside (HP) and isoquercitrin (IQ), in hawthorn fruits and a canned hawthorn drink were evaluated during 6 months of storage in the dark at three different temperatures (4, 23 and 40 °C). HPLC with a diode-array detector was used to determine the contents of the individual compounds. The results showed that the studied phenolics in the hawthorn fruits and the drink were both stable at 4 °C and relatively unstable at 23 and 40 °C with varied extents of degradation. At room temperature (23 °C), marked degradations of EC and PC-B2 were observed in both the fruits and the drink with around 50% and 30% decrease after a 6-month storage, respectively. A more significant decrease of the phenolics was observed at 40 °C, especially for EC and PC-B2, which were almost completely degraded after a 6-month storage. HP, IQ and ChA were relatively stable at 23 °C, but unstable at 40 °C. Therefore, low-temperature storage is recommended for maintaining the quality and efficacy of hawthorn fruits and its preparations. 相似文献